1. Field of the Invention
This invention relates to a process for reacting chloral with nitrogen compositions.
2. Description of the Prior Art
U.S. Pat. No. 4,152,497 discloses that certain reaction products of chloral with urea, thiourea, or sulfamide are useful as reactive flame retardants for polyurethane foams. The disclosed solid mono or dichloral urea compositions have the disadvantage of being prepared in water or tetrahydrofuran. In the case where these products are prepared in water, they must be filtered, dried and redissolved in the polyol before being used in the preparation of polyurethane foam. The acid catalyst used in their preparation also has to be removed by washing and this process step results in a disposal problem because a large volume of highly acidic wash water is generated. Another problem with these solid products is that substantially all the water has to be removed prior to dissolving them in the polyurethane polyols since it interferes with the foaming reaction. This necessitates a lengthy drying period. When tetrahydrofuran is used as the solvent, it has to be removed by distillation in order to isolate the product. This also creates a disposal problem. In addition, tetrahydrofuran is flammable and dangerous to handle in plant equipment making this process undesirable commercially.
Copending application Ser. No. 064,656 discloses flame retardant chloral urea compositions more conveniently prepared directly in an anhydrous polyol solution which comprises 20-95% of the total. In this disclosed process there is no need for filtration, washing or drying of the products prior to using them in the manufacture of polyurethane foams. This process has the disadvantage of not producing 100% active flame retardant.
East German Pat. No. 131,646 described a solventless process for preparing dichloralurea by the reaction of urea with technical chloral hydrate. This process as in the case of U.S. Pat. No. 4,152,497 has the disadvantage in that the product contains aqueous hydrochloric acid and must be thoroughly washed and dried before use in preparing polyurethane foam. If washing is omitted and the product only dried then the residual hydrochloric acid would interfere in the polyurethane foaming reaction since it would react and consume the necessary amine catalysts.
The present invention overcomes the disadvantages of the prior art by providing a process for preparing a 100% active product wherein urea and substituted ureas are reacted with anhydrous chloral in the absence of both solvents and acid catalysts. This invention also avoids the costly and time consuming washing and drying operations of the prior-art processes. In addition, since the reaction product contains no unreacted starting materials recovery or disposal operations are not required in the process of this invention; it is thus more economical.